A crown fits over the entire top of the tooth
above the gum line. Crownscover, protect,
seal and strengthen a tooth. A crown is needed when
a filling just will not
work. A crown may be made of gold, white porcelain,
or porcelain fused to gold. There are many situations
that may call for a crown:

Large decay.
If a tooth has decay so deep and large that a filling will not stay, or if the tooth structure is weakened,
a crown must be placed on the tooth to save it.

Large old fillings.
When large old fillings break down, or get decay around them, they usually need to be crowned. It
is important to crown a tooth that has been structurally
weakened to prevent a cracked or broken tooth. Once
a tooth breaks, it may not be possible to save it.

Cracked tooth.
When a tooth is cracked, a filling will not seal the crack. A crown has to be placed
over the tooth to hold it and the crack together.
If a crown is not placed on the tooth, the tooth
will become sensitive to chewing pressure, or will
eventually break. It is important to crown a cracked
tooth before it breaks, because in some cases
a broken tooth cannot be crowned and must be extracted.

Broken / Fractured tooth.
A tooth that has broken is usually too weak to hold
a filling. A crown will hold
the tooth together and prevent it from breaking again.
If the fracture involves the nerve, Root
Canal Therapy may be required before the tooth is
crowned. In some cases, a broken tooth cannot be saved
and must be extracted.

This patient chose not to have the cracked tooth
above crowned, and it later fractured. This tooth
had to be extracted because it cracked all the way
to the root.

Sensitive teeth.
Teeth that are very sensitive, either from a lot of
"wear", or from receded gums, sometimes require crowns
to seal and protect the teeth from hot and cold sensitivity.

Root Canal Therapy.
A tooth that has undergone Root Canal Therapy will need
a crown to properly seal and protect the tooth. A tooth
with Root Canal Therapy is more brittle than a tooth
with a healthy nerve and blood supply. A crown provides
the necessary support to the tooth.

In cosmetic dentistry,crowns(sometimes
called "caps") are used less frequently
since the advent of veneers,
but in some cases a crown may be necessary for a particular
tooth. A tooth with a bad fracture or a large filling may be
a candidate for a crown instead of a veneer.

beforeThis tooth has a large filling
as shown. A crown is needed on this tooth, instead
of a veneer, because there isn't enough natural
tooth left to support a veneer. A crown will cover
and protect the tooth, but will look the same as
a veneer.

afterThe top teeth now have veneers,
except the one that had the large filling, which
now has a crown.